mirror of
https://github.com/mozilla/gecko-dev.git
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413 lines
16 KiB
C++
413 lines
16 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "WebGLContext.h"
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#include "WebGLTexelConversions.h"
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namespace mozilla {
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using namespace WebGLTexelConversions;
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namespace {
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/** @class WebGLImageConverter
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*
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* This class is just a helper to implement WebGLContext::ConvertImage below.
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*
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* Design comments:
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*
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* WebGLContext::ConvertImage has to handle hundreds of format conversion paths.
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* It is important to minimize executable code size here. Instead of passing
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* around a large number of function parameters hundreds of times, we create a
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* WebGLImageConverter object once, storing these parameters, and then we call
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* the run() method on it.
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*/
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class WebGLImageConverter {
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const size_t mWidth, mHeight;
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const void* const mSrcStart;
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void* const mDstStart;
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const ptrdiff_t mSrcStride, mDstStride;
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bool mAlreadyRun;
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bool mSuccess;
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/*
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* Returns sizeof(texel)/sizeof(type). The point is that we will iterate over
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* texels with typed pointers and this value will tell us by how much we need
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* to increment these pointers to advance to the next texel.
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*/
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template <WebGLTexelFormat Format>
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static size_t NumElementsPerTexelForFormat() {
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switch (Format) {
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case WebGLTexelFormat::A8:
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case WebGLTexelFormat::A16F:
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case WebGLTexelFormat::A32F:
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case WebGLTexelFormat::R8:
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case WebGLTexelFormat::R16F:
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case WebGLTexelFormat::R32F:
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case WebGLTexelFormat::RGB565:
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case WebGLTexelFormat::RGB11F11F10F:
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case WebGLTexelFormat::RGBA4444:
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case WebGLTexelFormat::RGBA5551:
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return 1;
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case WebGLTexelFormat::RA8:
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case WebGLTexelFormat::RA16F:
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case WebGLTexelFormat::RA32F:
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case WebGLTexelFormat::RG8:
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case WebGLTexelFormat::RG16F:
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case WebGLTexelFormat::RG32F:
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return 2;
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case WebGLTexelFormat::RGB8:
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case WebGLTexelFormat::RGB16F:
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case WebGLTexelFormat::RGB32F:
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return 3;
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case WebGLTexelFormat::RGBA8:
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case WebGLTexelFormat::RGBA16F:
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case WebGLTexelFormat::RGBA32F:
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case WebGLTexelFormat::BGRX8:
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case WebGLTexelFormat::BGRA8:
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return 4;
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default:
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MOZ_ASSERT(false, "Unknown texel format. Coding mistake?");
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return 0;
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}
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}
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/*
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* This is the completely format-specific templatized conversion function,
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* that will be instantiated hundreds of times for all different combinations.
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* It is important to avoid generating useless code here. In particular, many
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* instantiations of this function template will never be called, so we try
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* to return immediately in these cases to allow the compiler to avoid
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* generating useless code.
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*/
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template <WebGLTexelFormat SrcFormat, WebGLTexelFormat DstFormat,
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WebGLTexelPremultiplicationOp PremultiplicationOp>
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void run() {
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// check for never-called cases. We early-return to allow the compiler
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// to avoid generating this code. It would be tempting to abort() instead,
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// as returning early does leave the destination surface with uninitialized
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// data, but that would not allow the compiler to avoid generating this
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// code. So instead, we return early, so Success() will return false, and
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// the caller must check that and abort in that case. See
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// WebGLContext::ConvertImage.
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if (SrcFormat == DstFormat &&
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PremultiplicationOp == WebGLTexelPremultiplicationOp::None) {
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// Should have used a fast exit path earlier, rather than entering this
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// function. we explicitly return here to allow the compiler to avoid
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// generating this code
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return;
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}
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// Only textures uploaded from DOM elements or ImageData can allow DstFormat
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// != SrcFormat. DOM elements can only give BGRA8, BGRX8, A8, RGB565
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// formats. See DOMElementToImageSurface. ImageData is always RGBA8. So all
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// other SrcFormat will always satisfy DstFormat==SrcFormat, so we can avoid
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// compiling the code for all the unreachable paths.
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const bool CanSrcFormatComeFromDOMElementOrImageData =
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SrcFormat == WebGLTexelFormat::BGRA8 ||
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SrcFormat == WebGLTexelFormat::BGRX8 ||
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SrcFormat == WebGLTexelFormat::A8 ||
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SrcFormat == WebGLTexelFormat::RGB565 ||
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SrcFormat == WebGLTexelFormat::RGBA8;
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if (!CanSrcFormatComeFromDOMElementOrImageData && SrcFormat != DstFormat) {
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return;
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}
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// Likewise, only textures uploaded from DOM elements or ImageData can
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// possibly have to be unpremultiplied.
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if (!CanSrcFormatComeFromDOMElementOrImageData &&
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PremultiplicationOp == WebGLTexelPremultiplicationOp::Unpremultiply) {
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return;
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}
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// there is no point in premultiplication/unpremultiplication
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// in the following cases:
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// - the source format has no alpha
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// - the source format has no color
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// - the destination format has no color
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if (!HasAlpha(SrcFormat) || !HasColor(SrcFormat) || !HasColor(DstFormat)) {
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if (PremultiplicationOp != WebGLTexelPremultiplicationOp::None) {
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return;
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}
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}
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// end of early return cases.
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MOZ_ASSERT(!mAlreadyRun, "converter should be run only once!");
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mAlreadyRun = true;
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// gather some compile-time meta-data about the formats at hand.
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using SrcType = typename DataTypeForFormat<SrcFormat>::Type;
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using DstType = typename DataTypeForFormat<DstFormat>::Type;
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const WebGLTexelFormat IntermediateSrcFormat =
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IntermediateFormat<SrcFormat>::Value;
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const WebGLTexelFormat IntermediateDstFormat =
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IntermediateFormat<DstFormat>::Value;
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using IntermediateSrcType =
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typename DataTypeForFormat<IntermediateSrcFormat>::Type;
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using IntermediateDstType =
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typename DataTypeForFormat<IntermediateDstFormat>::Type;
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const size_t NumElementsPerSrcTexel =
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NumElementsPerTexelForFormat<SrcFormat>();
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const size_t NumElementsPerDstTexel =
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NumElementsPerTexelForFormat<DstFormat>();
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const size_t MaxElementsPerTexel = 4;
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MOZ_ASSERT(NumElementsPerSrcTexel <= MaxElementsPerTexel,
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"unhandled format");
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MOZ_ASSERT(NumElementsPerDstTexel <= MaxElementsPerTexel,
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"unhandled format");
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// we assume that the strides are multiples of the sizeof of respective
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// types. this assumption will allow us to iterate over src and dst images
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// using typed pointers, e.g. uint8_t* or uint16_t* or float*, instead of
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// untyped pointers. So this assumption allows us to write cleaner and safer
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// code, but it might not be true forever and if it eventually becomes
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// wrong, we'll have to revert to always iterating using uint8_t* pointers
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// regardless of the types at hand.
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MOZ_ASSERT(
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mSrcStride % sizeof(SrcType) == 0 && mDstStride % sizeof(DstType) == 0,
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"Unsupported: texture stride is not a multiple of sizeof(type)");
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const ptrdiff_t srcStrideInElements =
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mSrcStride / static_cast<ptrdiff_t>(sizeof(SrcType));
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const ptrdiff_t dstStrideInElements =
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mDstStride / static_cast<ptrdiff_t>(sizeof(DstType));
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// Pop quiz: What's `ptrdiff_t(-16) / sizeof(int32_t)`?
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// Did you guess +4611686018427387900?
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MOZ_ASSERT(bool(srcStrideInElements < 0) == bool(mSrcStride < 0));
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MOZ_ASSERT(bool(dstStrideInElements < 0) == bool(mDstStride < 0));
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const SrcType* srcRowStart = static_cast<const SrcType*>(mSrcStart);
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DstType* dstRowStart = static_cast<DstType*>(mDstStart);
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// the loop performing the texture format conversion
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for (size_t i = 0; i < mHeight; ++i) {
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const SrcType* srcRowEnd = srcRowStart + mWidth * NumElementsPerSrcTexel;
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const SrcType* srcPtr = srcRowStart;
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DstType* dstPtr = dstRowStart;
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while (srcPtr != srcRowEnd) {
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// convert a single texel. We proceed in 3 steps: unpack the source
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// texel so the corresponding interchange format (e.g. unpack RGB565 to
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// RGBA8), convert the resulting data type to the destination type (e.g.
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// convert from RGBA8 to RGBA32F), and finally pack the destination
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// texel (e.g. pack RGBA32F to RGB32F).
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IntermediateSrcType unpackedSrc[MaxElementsPerTexel];
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IntermediateDstType unpackedDst[MaxElementsPerTexel];
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// unpack a src texel to corresponding intermediate src format.
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// for example, unpack RGB565 to RGBA8
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unpack<SrcFormat>(srcPtr, unpackedSrc);
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// convert the data type to the destination type, if needed.
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// for example, convert RGBA8 to RGBA32F
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convertType(unpackedSrc, unpackedDst);
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// pack the destination texel.
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// for example, pack RGBA32F to RGB32F
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pack<DstFormat, PremultiplicationOp>(unpackedDst, dstPtr);
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srcPtr += NumElementsPerSrcTexel;
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dstPtr += NumElementsPerDstTexel;
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}
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srcRowStart += srcStrideInElements;
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dstRowStart += dstStrideInElements;
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}
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mSuccess = true;
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}
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template <WebGLTexelFormat SrcFormat, WebGLTexelFormat DstFormat>
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void run(WebGLTexelPremultiplicationOp premultiplicationOp) {
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#define WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(PremultiplicationOp) \
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case PremultiplicationOp: \
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return run<SrcFormat, DstFormat, PremultiplicationOp>();
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switch (premultiplicationOp) {
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WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(
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WebGLTexelPremultiplicationOp::None)
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WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(
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WebGLTexelPremultiplicationOp::Premultiply)
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WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(
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WebGLTexelPremultiplicationOp::Unpremultiply)
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default:
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MOZ_ASSERT(false, "unhandled case. Coding mistake?");
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}
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#undef WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP
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}
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template <WebGLTexelFormat SrcFormat>
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void run(WebGLTexelFormat dstFormat,
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WebGLTexelPremultiplicationOp premultiplicationOp) {
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#define WEBGLIMAGECONVERTER_CASE_DSTFORMAT(DstFormat) \
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case DstFormat: \
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return run<SrcFormat, DstFormat>(premultiplicationOp);
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switch (dstFormat) {
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// 1-channel formats
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A8)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A16F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A32F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R8)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R16F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R32F)
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// 2-channel formats
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA8)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA16F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA32F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RG8)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RG16F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RG32F)
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// 3-channel formats
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB565)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB8)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB11F11F10F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB16F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB32F)
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// 4-channel formats
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA4444)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA5551)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA8)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA16F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA32F)
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WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::BGRA8)
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default:
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MOZ_ASSERT(false, "unhandled case. Coding mistake?");
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}
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#undef WEBGLIMAGECONVERTER_CASE_DSTFORMAT
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}
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public:
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void run(WebGLTexelFormat srcFormat, WebGLTexelFormat dstFormat,
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WebGLTexelPremultiplicationOp premultiplicationOp) {
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#define WEBGLIMAGECONVERTER_CASE_SRCFORMAT(SrcFormat) \
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case SrcFormat: \
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return run<SrcFormat>(dstFormat, premultiplicationOp);
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switch (srcFormat) {
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// 1-channel formats
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A8)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A16F)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A32F)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R8)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R16F)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R32F)
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// 2-channel formats
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA8)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA16F)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA32F)
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// 3-channel formats
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB565)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB8)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB16F)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB32F)
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// 4-channel formats
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA4444)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA5551)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA8)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA16F)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA32F)
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// DOM element source formats
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::BGRX8)
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WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::BGRA8)
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default:
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MOZ_ASSERT(false, "unhandled case. Coding mistake?");
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}
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#undef WEBGLIMAGECONVERTER_CASE_SRCFORMAT
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}
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WebGLImageConverter(size_t width, size_t height, const void* srcStart,
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void* dstStart, ptrdiff_t srcStride, ptrdiff_t dstStride)
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: mWidth(width),
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mHeight(height),
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mSrcStart(srcStart),
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mDstStart(dstStart),
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mSrcStride(srcStride),
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mDstStride(dstStride),
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mAlreadyRun(false),
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mSuccess(false) {}
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bool Success() const { return mSuccess; }
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};
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} // end anonymous namespace
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bool ConvertImage(size_t width, size_t height, const void* srcBegin,
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size_t srcStride, gl::OriginPos srcOrigin,
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WebGLTexelFormat srcFormat, bool srcPremultiplied,
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void* dstBegin, size_t dstStride, gl::OriginPos dstOrigin,
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WebGLTexelFormat dstFormat, bool dstPremultiplied,
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bool* const out_wasTrivial) {
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*out_wasTrivial = true;
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if (srcFormat == WebGLTexelFormat::FormatNotSupportingAnyConversion ||
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dstFormat == WebGLTexelFormat::FormatNotSupportingAnyConversion) {
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return false;
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}
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if (!width || !height) return true;
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const bool shouldYFlip = (srcOrigin != dstOrigin);
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const bool canSkipPremult =
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(!HasAlpha(srcFormat) || !HasColor(srcFormat) || !HasColor(dstFormat));
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WebGLTexelPremultiplicationOp premultOp;
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if (canSkipPremult) {
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premultOp = WebGLTexelPremultiplicationOp::None;
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} else if (!srcPremultiplied && dstPremultiplied) {
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premultOp = WebGLTexelPremultiplicationOp::Premultiply;
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} else if (srcPremultiplied && !dstPremultiplied) {
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premultOp = WebGLTexelPremultiplicationOp::Unpremultiply;
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} else {
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premultOp = WebGLTexelPremultiplicationOp::None;
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}
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const uint8_t* srcItr = (const uint8_t*)srcBegin;
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const uint8_t* const srcEnd = srcItr + srcStride * height;
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uint8_t* dstItr = (uint8_t*)dstBegin;
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ptrdiff_t dstItrStride = dstStride;
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if (shouldYFlip) {
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dstItr = dstItr + dstStride * (height - 1);
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dstItrStride = -dstItrStride;
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}
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if (srcFormat == dstFormat &&
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premultOp == WebGLTexelPremultiplicationOp::None) {
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// Fast exit path: we just have to memcpy all the rows.
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const auto bytesPerPixel = TexelBytesForFormat(srcFormat);
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const size_t bytesPerRow = bytesPerPixel * width;
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while (srcItr != srcEnd) {
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memcpy(dstItr, srcItr, bytesPerRow);
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srcItr += srcStride;
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dstItr += dstItrStride;
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}
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return true;
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}
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*out_wasTrivial = false;
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WebGLImageConverter converter(width, height, srcItr, dstItr, srcStride,
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dstItrStride);
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converter.run(srcFormat, dstFormat, premultOp);
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if (!converter.Success()) {
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// the dst image may be left uninitialized, so we better not try to
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// continue even in release builds. This should never happen anyway,
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// and would be a bug in our code.
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MOZ_CRASH("programming mistake in WebGL texture conversions");
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}
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return true;
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}
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} // end namespace mozilla
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